A folding knife is a cutting tool in which the blade is connected to the handle through a pivot, allowing the blade to fold into the handle. To prevent injury to the user's hand caused by accidental closing, folding knives typically have a locking mechanism. Different locking mechanisms are favored by various individuals for reasons such as perceived strength (lock safety) and ease of use (ergonomics). Knife manufacturers will also consider costs to make the components, tolerances, durability and possible warranty claims.
Inventors have come up with various designs of locking mechanisms for folding knives Several of the latest inventions focus on improving the ergonomics of operation, especially on opening and closing the blade with one hand, by building a thumb stud into the forward portion of the handle. However most of these designs are complicated in structure, requiring a large number of parts, and use small unreliable omega springs. As a result, the knives are difficult to manufacture, and result in higher production cost compared to older and simpler designs.